Masses

Masses are associated with the "masses" key in the model inputs, and must adhere to the following metadata schema:

Metadata for masses

Metadata	Names	Description
keys	"_"	the keys must have a single dimension named "_", with a single entry set to 0. Masses are always a metatensor.torch.TensorMap with a single block.
samples	["system", "atom"]	the samples must be named ["system", "atom"], since masses are always per-atom. "system" must range from 0 to the number of systems given as an input to the model. "atom" must range between 0 and the number of atoms/particles in the corresponding system. If selected_atoms is provided, then only the selected atoms for each system should be part of the samples.
components		the masses must not have any components
properties	"masses"	masses must have a single property dimension named "masses", with a single entry set to 0.

At the moment, masses are not integrated into any simulation engines.